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import rx.Observable;

import rx.Subscriber;

import java.util.ArrayList;

import java.util.List;

/**

*

* Exact example as 9 but uses the filter() operator to filter out nulls

* This example also explains the take() operator

* Created by matie on 26/04/15.

*/

public class example10 {

public static void main(String[] args){

//use the filter operator before the final printout which is expected to skip i == 2

query("rx-filter").flatMap(urls -> Observable.from(urls))

.flatMap(url -> getTitle(url))

.filter(title -> title != null)

.subscribe(title -> System.out.println(title));

System.out.println();

//take(n) - reads the first n items

query("rx-take").flatMap(urls -> Observable.from(urls))

.flatMap(url -> getTitle(url))

.filter(title -> title != null)

.take(3)

.subscribe(title -> System.out.println(title));

System.out.println();

}

//We could have used just() here, but I want the subscriber to ONLY print out my modified text.

private static Observable<String> getTitle(String Url){

return Observable.create(subscriber -> mapUrlToTitle(subscriber, Url));

}

private static void mapUrlToTitle(Subscriber<? super String> subscriber, String url) {

if(!subscriber.isUnsubscribed()){

//return null if 404

if(!url.equals("404")){

subscriber.onNext("Example title for " + url);

}else{

subscriber.onNext(null);

}

subscriber.onCompleted();

}

}

/**

* Re-using the query method in this example

* I prefer the lambda expressions as they are easier to extend. ANOTHER PLUS.

*/

private static Observable<List<String>> query(String text) {

return Observable.create(subscriber -> createAndEmitList(subscriber, text));

}

//I only have to deal with this part of the code and keep our query method untouched.

// If i == 2, I will print 404.

private static void createAndEmitList(Subscriber<? super List<String>> subscriber, String text){

List<String> myList = new ArrayList<String>();

for(int i = 0 ; i < 6 ; i++){

if(i == 2){

myList.add(404+"");

continue;

}

myList.add(text+ i + ".com");

}

if(!subscriber.isUnsubscribed()){

subscriber.onNext(myList);

subscriber.onCompleted();

}

}

}